Higher operating temperatures for gas turbine engines are continuously sought in order to increase efficiency. However, as operating temperatures increase, the high temperature durability of the components within the engine must correspondingly increase.
Significant advances in high temperature capabilities have been achieved through the formulation of nickel- and cobalt-based superalloys. For example, some gas turbine engine components may be made of high strength directionally solidified or single crystal nickel-based superalloys. These components are cast with specific external features to do useful work with the core engine flow and often contain internal cooling details and through-holes to provide external film cooling to reduce airfoil temperatures.
When exposed to the demanding conditions of gas turbine engine operation, particularly in the turbine section, the base alloy alone may be susceptible to damage, such as oxidation and corrosion attack, and may not retain adequate mechanical properties. Accordingly, the base alloys are often protected with various types of coating systems depending upon the engine part and operating environment.
Thus, engine components that operate at high temperatures often require environmental coatings to provide protection from oxidation and corrosion. The environmental coating may be used to provide further function as a bond coat for a thermal barrier coating. A typical example of these components is a cooled turbine blade.
The exterior surfaces of the blade frequently utilize a coating system such as platinum aluminide, MCrAlY overlay, or optimally an overlay NiAl based coating. This coating is often additionally coated with the TBC material, such as 7YSZ.
Scientists and engineers working under the direction of Applicant's Assignee and continually seeking new bond coats having improved capabilities that can be applied to articles, such as gas turbine engine components, to withstand the harsh operating conditions of the engine, as well as methods for applying such bond coats to gas turbine engine components. The claimed invention fulfills this need and others.